CATV networks may be implemented with various techniques and network topologies, but currently most cable television networks are implemented as so-called HFC networks (Hybrid Fiber Coax), i.e. as combinations of a fibre network and a coaxial cable network. Data Over Cable Service Interface Specification (DOCSIS) is a CATV standard providing specifications for high-bandwidth data transfer in an existing CATV system. The latest version DOCSIS 3.1 enables the cable network operators to maximize both the downstream and upstream data throughput using the existing HFC networks.
The introduction of DOCSIS 3.1 raises the need to eventually adjust the frequency range and the bandwidth of the communication channels. The cable operators are willing to offer higher data rates for the upstream channels, and therefore they eventually will shift to use a higher upstream bandwidth supported by DOCSIS 3.1.
The upper frequency edge of the upstream bandwidth is controlled by diplex filters residing in network elements. Instead of maintenance personnel manually replacing the old diplex filters with new ones at each network element, it has been proposed that the network elements are provided with at least two diplex filters and the network elements are remotely controlled by a headend of the CATV network to select an appropriate diplex filter. However, there are a great number of CATV networks that do not support any kind of remote signalling.